virtualization.info just received a confirmation from a trusted source: VMware co-founder and Chief Scientist Mendel Rosenblum resigned.

His wife, Diane Greene, that founded the company with him and led it as CEO since 1998 was removed by the board of directors in July for much unclear reasons. After that, the risk that her husband would follow was very high.

VMware told virtualization.info that Rosenblum took a month of vacation immediately after that meeting, and this delayed the decision to leave the company.

Also, maybe fearing an impact on the upcoming VMworld 2008 in Las Vegas, VMware may have requested to postpone the resignation until the event registration was almost complete: this year VMworld achieved a ground-breaking record of 14,000 delegates so there’s no more need to wait.

While Diane Green was the keeper of the VMware culture and engineering tradition, Rosenblum was recognized as the company visionary, designing technologies to be implemented in the next few years.
For example, the upcoming security APIs called VMsafe, which has the potential to change the way we secure the data centers, were developed by the scientist in 2002.

virtualization.info was told that Rosenblum will go back working full-time to the university where he and his wife started VMware: Stanford.

With him VMware has already lost three key leaders.
The third one is the Executve Vice President of R&D, Richard Sarwal, who left just last week to go back to Oracle. Now it seems clear why.

This departure comes at the worst moment: yesterday Microsoft officially presented its competing product, Hyper-V, and while the hypervisor is still years behind the VMware technology, the entire industry announced support for it.
VMware will need a solid strategy to counter that: cutting-edge technologies rarely wins against Microsoft marketing war-machines and ubiquitous alliances.

Update: The New York Times reports that also Paul Chan, Vice President of Product Development will leave the company next month, after resigning in August.

Second update: After the news VMware lost almost 7% at Wall Street today: